Spools are a well known device for carrying and dispensing wound filaments, strands and the like. Spools are typically constructed of a spindle extending between two end pieces. A filament or strand is wound about the spool and, as needed, dispensed therefrom. Spools are used for a variety of materials, ranging from light weight threads to heavy metal cables. The spool must therefor be sufficiently rigid to support not only the weight of the spool itself, but to withstand the centripetal force exerted against it as a result of rapid unwinding of such varied types of wound material.
It is desirable that the spool be reusable. This often necessitates removal of the end pieces of tne spindle so that any residual material can be removed. Spools that can be so disassembled are often referred to "knock-down" spools and their use is well known. Even so, the use of knock-down spools for relatively heavy filaments or other like materials injects a tension into their construction. The spool must be sufficiently rigid to support the material and the spool itself, but also constructed so as to be readily disassembled.
Several spool assemblies known in the prior art purport to resolve this tension. U.S. Pat. No. 1,234,150 to Glaser discloses a spool formed of a spindle and two circular end flanges. Each end flange includes an inwardly projecting plug fitted with three hook-like rod elements. These elements serve to insure attachment of the plug to the end flange.
U.S. Pat. No. 3,905,561 to Kelch et al. discloses a tape carrier having a hollow core constructed separately from the end flanges. The core defines three recesses equally spaced about its axis. Each flange includes three resilient latches disposed and spaced peripherally of the core's aperture so as to secure the flange to the core for rotation therewith.
U.S. Pat. No. 4,128,215 to Underwood discloses a textile spool consisting of a pair of removable plugs inserted into the end of a hollow spindle. Each plug includes a flange and a tongue element. The tongue provides a raised projection positioned for engagement with an opening in the spindle. This arrangement provides for the plugs to be lockingly engaged with the spindle.
While each of these and the many other prior art spools purport to resolve the above described tension, several problems remain. Often, the fit between the various component parts is either loose initially or becomes so over time. This is typically due to the fact that such prior art spools do not positively interlock the end pieces to the spool. It is also sometimes due to the relatively complex arrangement of component parts provided by prior art spools. In an effort to overcome these problems, the components are often attached together utilizing an adhesive solvent or an ultrasound welding technique. While such techniques insure a tight fit, their use is expensive in both material and labor, and therefore, generally undesirable. Furthermore, once the components are so bounded together, they cannot be disassembled without breaking either the bond or the component.
Thus, there exists a need for a knock-down spool formed of a minimum number of parts that is not only easily assembled and tightly fit together, but can be easily disassembled and reassembled.